2004-02-24_REVISION - M1977153 (4)

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Geotechnical Data Technical Memorandum Hazeltine -Road Runners Rest II Gravel Pit Lining Project December 2000 3.2.1 Drilling Methods Borings were drilled with a Mobil B57 truck-mounted drill rig and advanced through soils using 4'/<-inch-inside-diameter, hollow-stem auguring methods. Soil samples were obtained in advance of the augers at approximate 2- to 24-inch intervals by driving a standard split-spoon sampler in general accordance to the procedures of ASTM D1586. A representative portion of each split-spoon sample was sealed in a plastic bag. Borings were generally advanced through the upper 1 to 6 feet of intensely weathered bedrock using the hollow-stem augering and standard split-spoon sampling methods described above. Borings were advanced through less weathered bedrock using two different sized wireline rock coring methods. Borings B-101 through B-104 were advanced with CN-sized (1.875-inch-inside-diameter) rock coring methods, and Borings B-105 through B-120 were advanced with NX-sized (2,000-inch-inside-diameter) rock coring methods. Rock core was obtained in increments of 5 feet or less and water was used as a drilling fluid. Upon completion of drilling and packer permeability testing, the boring was either backfilled with cement-bentonite grout or a piezometer was installed (see Table 3.1). 3.2.2 Logging Procedures Concurrent with drilling, GEI's Field Engineer prepared field logs for each boring. Soil and bedrock samples were visually classified and sample locations, depth of groundwater at the time of drilling, and other pertinent information was recorded. Bedrock core samples were logged to identify subsurface stratigraphy and to observe features important in evaluation of rock mass properties, such as weathering and fracturing. Percent sample recovery, rock quality designation (RQD), coring time, drilling observations, and descriptions of the soil and rock encountered during drilling are presented in the boring logs in Appendix A. 3.2.3 Packer Testing Procedures Upon completion of drilling, packer permeability tests were performed in the bedrock portion of each boring to estimate the in situ hydraulic conductivity of the bedrock. Test intervals were typically 5- to 15-feet long. In general, two zones were tested: the upper 10 feet and the lower 10 feet portions of bedrock. Five water pressures were applied for each test interval: approximately 50, 75, 90, 75, and 50 percent of the estimated effective overburden pressure. Table 4.6 provides a summary of the packer permeability tests. Data and test results are also presented in Appendix B. oe'-'sg`"-`"`"T" 3 3 ~ GEI Consultants, Inc.